Scientists have described a new species of annual killifish from southern Brazil.

Killifish expert Wilson Costa of the Department of Zoology at the University of Rio de Janeiro and Morevy Cheffe described the new killi as Austrolebias univentripinnis in a paper in the latest issue of the journal Zootaxa.

The new Austrolebias was discovered from the floodplains of the Rio Jaguarao in the Lagoa Mirim (Lake Mirim) basin in the south of Brazil.

The fish is a member of the cyprinodontiform family Rivulidae and is believed to be a member of an evolutionary group (called a clade) which includes A. viarius, A. charrua, A. bellottii, A. melanoorus, A. vandenbergi, A. nigrofasciatus, A. minuano, A. arachan and A. adloffi.

All of the fishes in this clade have a characteristic long and triangular anal fin in females.

Costa and Cheffe say that Austrolebias univentripinnis is similar to bellottii and melanoorus as males have a urogenital papilla which is completely attached to the anal fin.

The males of univentripinnis have different markings on their unpaired fins and both sexes differ in colouration from melanoorus.

For more details on the new species see the paper: Costa, WJEM and MM Cheffe (2005) - Austrolebias univentripinnis sp. nov. (Teleostei: Cyprinodontiformes: Rivulidae): a new annual killifish from the Mirim Lagoon basin, southern Brazil. Zootaxa 1052: 41-48.